1. Field of the Invention
The present invention relates to a fractional frequency divider and to a method of fractional frequency division.
2. Discussion of the Related Art
Fractional frequency dividers allow the frequency of a timing signal to be divided by non-integer values. They generally operate by pulse swallowing, in other words by selecting only certain pulses of the original timing signal to be included in the reduced frequency timing signal. This is achieved using an integer divider in which the divisor of the division operation is varied between two or more integer values such that the average divisor has the desired non-integer value.
A challenge with dividing the frequency of a timing signal using fractional frequency dividers is to avoid noise in the frequency bands of interest. Previous attempts to overcome this noise problem involve choosing a certain distribution of the two or more divisor values of the integer divider. However, such solutions tend to be inadequate, and there is thus a need for an improved fractional frequency divider that generates a reduced frequency timing signal with reduced noise in the frequency bands of interest, and without greatly increasing the size and complexity of the frequency divider.